A journal tends to create the person rather than the person creates a journal. This is because it is in reflection that we discover what we think and know about ourselves.
Journaling builds a life from the outside and there does not have to be a blueprint. The act is enough and serves to bring us towards whatever we find interesting, or of note. Whether at night, when things are still, or at some random hour amongst the bustle of the day. We may come to find ourselves more interesting, or find we are just as excruciating as we thought.
Reflecting on experience gives us a viewpoint to understand what we take pleasure in, who we take pleasure in, and why we take pleasure in these things. The necessity of thought colours our world; we know something of our interests; what compels our attention. If we chose to write, we are forming a relationship with ourselves that we can look back on.